JPH11219720A - Battery and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery whose voltage drop at the time when a large current is applied is suppressed to low, by lessening the number of welding points and the number of parts and lowering the electric resistance between electrode plates and the terminal parts. SOLUTION: No active material layer 6b is formed on the surface of a negative electrode collector 6a made of a strip-like metal foil and a bottom face side exposed part 6c is formed while being projected in the bottom face 3d side of an electrolytic bath case 1 out of a rolled electrode plate unit 2. The bottom face side exposed part 6c is welded with the bottom face 3d of a battery can main body 3 to directly connect the negative electrode collector 6a with the battery can main body 3. No active material layer 4b is formed on the surface of a positive electrode collector 4a made of a strip-like metal foil and a terminal member side exposed part 4c is formed while being projected in the terminal member 5 side of an electrolytic bath case 1 from the rolled electrode plate unit 2. The terminal member side exposed part 4c is welded with a connection part 5a of the terminal member 5 to directly connect the positive electrode collector 4a with the terminal member 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a battery and a lithium ion battery, and more particularly to a battery having a spiral electrode group and a lithium ion battery.

[0002]

2. Description of the Related Art In recent years, batteries having a high energy density, such as lithium ion batteries, have been frequently used in portable equipment.
In a battery having such a high energy density, a metal foil having a thickness of 10 to 20 μm is used as a positive electrode current collector and a negative electrode current collector in order to reduce the size of the entire battery. In a battery of this type, a spiral electrode plate group in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween is usually used. It is trying to connect with. First, a positive electrode plate and a negative electrode plate each having one end of a strip-shaped lead member attached to each of the positive electrode current collector and the negative electrode current collector by welding or the like are wound to form a spiral electrode group. Next, the other end of the lead member is welded to the battery can body and the terminal member attached to the battery can body, respectively. When a single current collecting method is adopted for a battery having a high energy density, a lead member is connected to a plurality of locations of each current collector, and the plurality of lead members are bundled at one location to form a battery can body and a terminal. By welding to the members, high-rate discharge of the battery is supported. However, since the spiral electrode group has a variation in thickness, it is difficult to bundle a plurality of lead members in one place. Therefore, it is difficult to increase the number of lead members, and there is a limit in increasing the current collecting capability. Further, in order to eliminate the displacement of the plurality of lead members, it is necessary to adjust the length of each lead member. Therefore, as shown in JP-A-8-115744,
An exposed portion where no active material is formed is formed at the end of the current collector in the width direction, and a lead wire is spirally resistance-welded along the exposed portion, and the lead wire is connected to each terminal of the battery case by a connecting member. It was proposed to connect through.

[0003]

However, in such a method, there are many welding points, and the manufacture of the battery becomes complicated. In addition, there is a problem that lead wires and connection members are required, and the number of parts increases. In addition, the electrical resistance of the connection between the electrode plate and the terminal portion (the battery can body and the terminal member) was high, and the voltage drop when a large current was passed was large.

An object of the present invention is to provide a battery and a lithium ion battery which can be easily manufactured by reducing the number of welding points and the number of parts.

Another object of the present invention is to provide a battery and a lithium ion battery which can reduce the electric resistance between the electrode plate and the terminal portion to reduce the voltage drop when a large current flows. .

[0006]

SUMMARY OF THE INVENTION The present invention provides a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector made of a strip-shaped metal foil, and a negative electrode active material formed on a negative electrode current collector made of a strip-shaped metal foil. A spiral electrode group formed by winding a negative electrode plate having a material layer formed thereon through a separator, and a current collector containing the spiral electrode group and accommodating one of a positive electrode current collector and a negative electrode current collector A battery can body electrically connected to the body, and a terminal member electrically connected to the other current collector of the positive electrode current collector and the negative electrode current collector and attached to the battery can body via an insulating material. The battery to be equipped. In the present invention, one of the current collectors of the positive electrode current collector and the negative electrode current collector does not have an active material layer formed on its surface, and has a first exposed portion protruding from one end of the spiral electrode group. The other of the positive electrode current collector and the negative electrode current collector has an active material layer formed on the surface thereof, and the second current collector projects from the other end of the spiral electrode group. It has an exposed part integrally.
Then, the first exposed portion and the second exposed portion are directly connected to the terminal member and the battery can body, respectively. If the exposed portion is formed on the current collector as in the present invention and the exposed portion is directly connected to the terminal member and the battery can body, it is not necessary to use a lead wire and a connecting member as in the related art, so that the number of parts is small. Can be reduced. In addition, when the current collector of the electrode plate is directly connected to the terminal portion (terminal member and battery can body) of the battery, the electric resistance between the electrode plate and the terminal portion can be reduced, and a large current flows. The voltage drop at the time can be reduced.

When the first exposed portion and the second exposed portion of the current collector are formed to be long along the longitudinal direction of the current collector, they protrude in a spiral shape, so that the battery can body It is not easy to directly connect each exposed portion to the terminal member.
In order to facilitate direct connection in such a case, the following configuration can be adopted. For example, when at least one of the first exposed portion and the second exposed portion extends along the longitudinal direction of the corresponding current collector, the exposed portion extends in a direction orthogonal to the longitudinal direction. What is necessary is just to divide by a some slit. Further, at least one of the first exposed portion and the second exposed portion may be constituted by a plurality of projecting pieces arranged at intervals in the longitudinal direction of the current collector. With such a configuration, the first exposed portion and the second exposed portion can be easily bent, and welding can be facilitated. In addition, at least one of the first exposed portion and the second exposed portion may be formed so that the protruding length becomes longer from the inner diameter portion side to the outer diameter portion side of the spiral electrode group. . With this configuration, the length of the exposed portion on the inner diameter side of the spiral electrode group is reduced, and the length of the exposed portion on the outer diameter side of the spiral electrode group is increased. As a result, it becomes easy to concentrate and weld the exposed portion to the center of the terminal member or the bottom of the battery can body. Further, at least one of the first exposed portion and the second exposed portion may be formed partially only on the inner diameter side of the spirally wound electrode group.

The present invention can be suitably used for a lithium ion battery having a high energy density. The specific configuration of the lithium ion battery includes a positive electrode plate in which a positive electrode active material layer for absorbing and releasing lithium ions is formed on a positive electrode current collector made of a band-shaped metal foil, and a negative electrode current collector made of a band-shaped metal foil A negative electrode plate on which a negative electrode active material layer containing a carbon material that occludes and releases lithium ions is formed, and a spiral electrode plate group formed by winding a negative electrode plate through a separator, and a spiral electrode plate group are housed therein. A battery can body electrically connected to one of the positive electrode current collector and the negative electrode current collector; and a battery can body electrically connected to the other of the positive electrode current collector and the negative electrode current collector Further, the present invention is directed to a lithium ion battery including a terminal member attached to a battery can body via an insulating material. Then, the active material layer is not formed on the surface of one of the positive electrode current collector and the negative electrode current collector, and the first exposed portion protruding from one end of the spiral electrode group is integrally formed. Has, the other of the positive electrode current collector and the negative electrode current collector, the active material layer is not formed on the surface,
The second exposed portion protruding from the other end of the spiral electrode group is integrally formed. Then, the first exposed portion and the second exposed portion are directly connected to the terminal member and the battery can body, respectively.

[0009]

(Embodiment 1) FIG. 1 is a sectional view of a battery according to the present embodiment in which the present invention is applied to a large capacity lithium ion battery. As shown in the figure, the battery of the present embodiment is configured such that a spiral electrode group 2 is housed in a battery case 1. The battery case 1 has a battery can body 3 having conductivity and a positive electrode terminal member 5 attached to the battery can body 3 via an insulating material 8. The battery can body 3 has a metal-made cylindrical body 3a having one end opened, and an annular metal lid 3b for closing the opening of the cylindrical body 3a. The positive electrode terminal member 5 has a columnar shape having a small-diameter portion at the center, and has a small-diameter convex portion at an end facing the spiral electrode plate group 2. The outer peripheral part of this convex part constitutes the connection part 5a.

The spiral electrode group 2 includes a positive electrode plate 4 and a negative electrode plate 6.
Are wound with a separator 7 interposed therebetween.
Positive electrode plate 4 is made of lithium cobaltate (LiCoO ₂ ) that occludes and releases lithium ions on both surfaces of a positive electrode current collector 4a made of a 20-μm-thick sheet-like strip-shaped aluminum foil.
Is formed by forming a positive electrode active material layer 4b containing.
The positive electrode current collector 4a has, at one end in the width direction, a first exposed portion that does not have an active material layer formed on its surface and protrudes from the spiral electrode group 2 toward the terminal member 5 and the lid 3b. It has a terminal member side exposed portion 4c to be configured. This terminal member side exposed portion 4c
Extends along the longitudinal direction of the positive electrode current collector 4a, and is divided by a plurality of slits extending in a width direction orthogonal to the longitudinal direction. Each divided piece divided by the slit of the terminal member side exposed portion 4c is bent so as to face the terminal member 5 side, and its ends 4d are connected to the connection portion 5a of the terminal member 5 in a state of being overlapped with each other. They are connected by welding. The connecting portion 5a of the terminal member 5 is provided on the terminal member side exposed portion 4c.
Will be described in detail in a later manufacturing method.

The negative electrode plate 6 has a structure in which a negative electrode active material layer 6b containing carbon powder for absorbing and releasing lithium ions is formed on both surfaces of a negative electrode current collector 6a formed of a 20-μm thick sheet-like strip-shaped copper foil. ing. The negative electrode current collector 6a has a second end protruding from the spiral electrode group 2 toward the bottom surface 3d of the battery case 1 without an active material layer formed at one end in the width direction.
The bottom surface side exposed part 6c which comprises the exposed part of this. Like the terminal member-side exposed portion 4c, the bottom-side exposed portion 6c also extends along the longitudinal direction of the negative electrode current collector 6a, and is divided by a plurality of slits extending in a width direction orthogonal to the longitudinal direction. Then, each of the divided pieces divided by the slit of the bottom side exposed portion 6c is bent so as to face the center side of the bottom surface 3d, and the end portions 6d are overlapped with each other on the bottom surface 3d of the battery case 1. They are connected by welding.

A method for manufacturing the battery of this embodiment will be described. First, the positive electrode plate 4 is manufactured as follows. First, 88 parts by weight of lithium cobaltate (LiCoO ₂ ) powder, 8 parts by weight of graphite powder, and 4 parts by weight of polyvinylidene fluoride are dispersed in a solvent composed of N-methylpyrrolidone to prepare a positive electrode mixture slurry. Next, thickness 20μm × width 340mm ×
On both sides of a positive electrode current collector 4a made of a strip-shaped aluminum foil having a length of 3400 mm, a terminal member-side exposed portion 4c having a width dimension of 40 mm without applying a positive electrode mixture slurry to one end in the width direction
Is applied so that the positive electrode mixture slurry has a substantially uniform thickness. Next, after drying, it was compressed in the thickness direction to a thickness of 200 μm. Next, the terminal member side exposed portion 4c
The positive electrode plate 4 was made by making slits (cuts) extending in the width direction at intervals of 20 mm.

Next, the negative electrode plate 6 is manufactured. First, particle size 1-5
A negative electrode mixture slurry is prepared by dispersing 90 parts by weight of carbon powder composed of spherical mesocarbon microbeads having a diameter of 0 μm and d ₀₀₂ = 3.366 Å and 10 parts by weight of polyvinylidene fluoride in a solution composed of N-methylpyrrolidone. Next, thickness 20μm × width 340mm × length 3600m
The width dimension 40 where the negative electrode mixture slurry is not applied to one end in the width direction on both surfaces of the negative electrode current collector 6a made of a strip-shaped copper foil having a width of 40 m.
The negative electrode mixture slurry is applied with a substantially uniform thickness so as to form the bottom exposed portion 6c of mm. Next, after drying, it was compressed in the thickness direction to a thickness of 120 μm. Next, slits (cuts) extending in the width direction at intervals of 20 mm were made in the terminal member-side exposed portions 4c to form the negative electrode plate 6.

Next, as shown in the schematic diagram of FIG. 2, a polyethylene microporous film (dimensions: thickness 25 μm × width 280 m)
m) a positive electrode plate 4 and a negative electrode plate 6
And spirally wound to form a spirally wound electrode plate group 2. The terminal member side exposed portion 4c of the positive electrode plate 4 and the bottom surface exposed portion 6c of the negative electrode plate 6 project beyond the separator 7 in different directions in the width direction. Next, the divided pieces of the bottom surface side exposed portion 6c of the negative electrode plate 6 were bent toward the center of the spiral electrode group 2 so as to overlap each other. And the bottom side exposed part 6c
The spirally wound electrode group 2 is placed in the cylindrical body 3a of the battery can body 3 so that the end 6d of the divided piece of the battery can contact the bottom 3d of the battery can body 3.
Insert inside. FIG. 3 is a cross-sectional view in which the spiral electrode group 2 is disposed in the cylindrical body 3a. As shown in FIG. 3, the end 6d of the bottom-side exposed portion 6c was irradiated with the YAG laser beam L1, and the end 6d was laser-welded to the bottom 3d.

Next, as shown in FIG. 4, the divided pieces of the terminal member-side exposed portion 4c are swirled so that the ends 4d of the divided pieces of the terminal member-side exposed portion 4c of the positive electrode plate 4 overlap each other. The group 2 was bent toward the center side, and its end 4d was connected to the connection 5a of the terminal member 5 having the lid 3b. In order to make this connection, first, the end of each divided piece is temporarily fixed to the connection portion 5a by an appropriate means such as a rubber band. Then, the end 4d of the terminal member side exposed portion 4c was irradiated with the YAG laser beam L2, and the end 4d was laser-welded to the connecting portion 5a.

Next, the peripheral edge of the lid 3b was laser-welded to the opening end of the cylindrical body 3a using a YAG laser beam. Then, an electrolyte obtained by dissolving 1 mol / l of lithium hexafluorophosphate in a mixed solvent of ethylene carbonate and dimethyl carbonate having a volume ratio of 1: 1 is injected from an injection port (not shown) provided in the terminal member 5. After that, the injection port was sealed to complete a lithium ion battery weighing 1.10 kg.

(Embodiment 2) In the battery of this embodiment, as shown in the schematic diagram of FIG. 5, the exposed portions 16c and 14c of the negative electrode plate 16 and the positive electrode plate 14 are spaced apart in the longitudinal direction of the current collector. A plurality of protruding pieces were arranged side by side, and the others were manufactured in the same manner as in Example 1. In the present embodiment, the length of the projecting pieces 16c and 14c is 800 mm, and the interval between the projecting pieces 16c and 14c is 200 mm.

(Embodiment 3) In the battery of this embodiment, as shown in the schematic diagram of FIG. 6, the exposed portions 26c and 24c of the negative electrode plate 26 and the positive electrode plate 24 are The tapered shape was formed such that the length of the protruding dimension became longer from the side toward the outer diameter side, and slits (cuts) extending in the width direction at intervals of 20 mm were formed. Others were manufactured similarly to Example 1.

(Embodiment 4) In the battery of this embodiment, as shown in the schematic diagram of FIG. 7, the exposed portions 36c and 34c of the negative electrode plate 36 and the positive electrode plate 34 are connected to the inner diameter side of the spiral electrode group 2. Only, and slits (cuts) extending in the width direction at intervals of 20 mm were formed. In addition to the above-described configuration, the first embodiment
Manufactured in the same manner as

(Comparative Example 1) As shown in the schematic diagram of FIG. 8, the battery of this comparative example extends in the width direction without providing the exposed portions at the width direction ends on the negative electrode plate 46 and the positive electrode plate 44. Exposed part 46
c and 44c were provided at three places. Then, a columnar lead member 8 of the same material as each base is welded to the exposed portions 46c and 44c by ultrasonic welding, and the end of the lead member 8 is connected to the bottom surface 3d of the battery case 1 and the connection portion 5a of the terminal member 5. Were welded by ultrasonic welding. And it manufactured like Example 1 except the said structure. The battery weight of this comparative example was 1.08 kg.

(Comparative Example 2) In the battery of this comparative example, an exposed portion having a width of 10 mm was provided at each of the ends in the width direction of the negative electrode plate and the positive electrode plate. Then, on the positive electrode plate, an aluminum lead wire having a width of 2 mm and a thickness of 0.26 mm is ultrasonically welded along the longitudinal direction of the exposed portion, and on the negative electrode plate, nickel having a width of 2 mm and a thickness of 0.30 mm is welded along the longitudinal direction of the exposed portion. The lead wire was resistance welded. Then, each lead wire was wound together with each electrode plate to form a spiral electrode group. Next, an aluminum connecting member having eight radially extending radiating portions and a cylindrical base positioned at the center of the radiating portion is prepared, and the radiating portions of the connecting members are ultrasonically connected to aluminum lead wires of the positive electrode plate. Welding was performed, and the base of the connection member was ultrasonically welded to the connection portion 5 a of the terminal member 5 to electrically connect the positive electrode plate to the terminal member 5.
Also, a nickel connection member similar to the above is prepared, and the radiating portion of the connection member is ultrasonically welded to the nickel lead wire of the negative electrode plate, and the base of the connection member is ultrasonically welded to the bottom surface 3d of the battery case 1. Then, the negative electrode plate was electrically connected to the battery case 1. And it manufactured like Example 1 except the said structure. In addition, the battery weight of this comparative example was 1.25 kg.

Next, a test was performed using each of the above batteries. First, each battery was charged at 7 A to 4.1 V, and then discharged at 7 A to 2.8 V at room temperature. The capacity obtained at this time was 35 Ah for all the batteries. Next, each battery was charged at 7A.
After charging to 1V, at 105A (corresponding to 3C) 2.
The battery was discharged at room temperature to 8 V, and the discharge capacity of each battery was measured.
The capacity retention ratio of 105A discharge to A discharge was examined. The surface temperature of each battery after the discharge in this test was measured using a thermocouple. Table 1 shows the measurement results.

Separately from the above test, each cell was 4.1 at 7A.
After charging to V, discharge at 7A for 3.5 hours to bring the depth of discharge to 70%, then 245A (corresponding to 7C)
For 30 seconds, the average discharge voltage was measured, and the output density of each battery at a discharge depth of 70% was measured. The impedance of each battery in a completely discharged state was measured using an alternating current of 1 kHz. Table 1 also shows the measurement results.

[0024]

[Table 1] From Table 1, it can be seen that the batteries of Examples 1 to 4 can increase the capacity retention of the 105A discharge with respect to the 7A discharge and lower the battery surface temperature after the discharge is completed, as compared with the batteries of Comparative Examples 1 and 2. You. It can also be seen that the output density at a discharge depth of 70% can be increased to lower the impedance in a completely discharged state. Therefore, when the batteries of Examples 1 to 4 are used, it can be seen that the electric resistance between the electrode plate and the terminal portion can be reduced, and the voltage drop when a large current flows can be reduced.

Although this embodiment is an example in which the present invention is applied to a relatively large battery, the present invention can of course be applied to a small cylindrical battery. In addition, it goes without saying that the present invention can also be applied to a battery in which the lid is formed of a terminal member.

Although the present embodiment is applied to a non-aqueous electrolyte battery comprising a lithium ion battery, the battery of the present invention can be applied to other batteries.

[0027]

According to the present invention, since the current collector is directly connected to the terminal member and the battery can main body, the number of welding points can be reduced, and it is not necessary to use a lead wire and a connecting member as in the prior art. Therefore, the number of parts can be reduced. In addition, the current collector of the electrode plate is connected to the battery terminal portion (terminal member and battery can body).
, The electric resistance between the electrode plate and the terminal portion can be reduced, and the current distribution can be made uniform. Therefore, the voltage drop when a large current flows can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a battery according to an embodiment of the present invention.

FIG. 2 is a schematic plan view used to explain an embodiment of forming a spiral electrode group of the battery according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view used to explain an embodiment of producing a battery according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view used to explain an embodiment of producing a battery according to an embodiment of the present invention.

FIG. 5 is a schematic plan view of an electrode plate used in a battery according to another embodiment of the present invention.

FIG. 6 is a schematic plan view of an electrode plate used in a battery according to still another embodiment of the present invention.

FIG. 7 is a schematic plan view of an electrode plate used in a battery according to still another embodiment of the present invention.

FIG. 8 is a schematic plan view of an electrode plate used for a battery of a comparative example.

[Explanation of symbols]

 2 spiral electrode group 3 battery can main body 3a cylindrical body 3b lid 3d bottom surface 5 positive terminal member 5a connecting portion 4 positive plate 4a positive current collector 4b positive active material layer 4c terminal member side exposed portion 6 negative plate 6a negative electrode Current collector 6b Negative electrode active material layer 6c Bottom side exposed portion 7 Separator

Claims (6)

[Claims] 1. A positive electrode plate in which a positive electrode active material layer is formed on a positive electrode current collector made of a band-shaped metal foil, and a negative electrode in which a negative electrode active material layer is formed on a negative electrode current collector made of a band-shaped metal foil A spirally wound electrode plate group formed by winding a plate with a separator therebetween, and the spirally wound electrode plate group is housed therein and electrically connected to one of the positive electrode current collector and the negative electrode current collector. A battery can body to be connected; and a terminal member electrically connected to the other of the positive electrode current collector and the negative electrode current collector and attached to the battery can body via an insulating material. In the battery, the first current collector of the positive electrode current collector and the one current collector of the negative electrode current collector do not have an active material layer formed on a surface thereof, and have a first shape that protrudes from one end of the spiral electrode group. An exposed portion is integrally provided, and the other current collector of the positive electrode current collector and the negative electrode current collector is: No active material layer is formed on the surface, and a second exposed portion projecting from the other end of the spiral electrode group is integrally provided, and the first exposed portion and the second exposed portion Is directly connected to the terminal member and the battery can body, respectively. 2. A plurality of at least one of the first exposed portion and the second exposed portion extends along a longitudinal direction of the corresponding current collector and extends in a direction orthogonal to the longitudinal direction. 2. The battery according to claim 1, wherein the battery is divided by a slit. 3. The method according to claim 1, wherein at least one of the first exposed portion and the second exposed portion is constituted by a plurality of projecting pieces arranged at intervals in a longitudinal direction of the current collector. The battery according to claim 1. 4. The at least one of the first exposed portion and the second exposed portion has a protruding length that increases from the inner diameter side to the outer diameter side of the spirally wound electrode plate group. The battery according to claim 2, wherein the battery is formed. 5. The apparatus according to claim 1, wherein at least one of the first exposed portion and the second exposed portion is partially formed only on the inner diameter side of the spiral electrode group. 2. The battery according to 1. 6. A positive electrode plate in which a positive electrode active material layer for absorbing and releasing lithium ions is formed on a positive electrode current collector made of a band-shaped metal foil, and lithium ions are formed on a negative electrode current collector made of a band-shaped metal foil. A negative electrode plate formed with a negative electrode active material layer containing a carbon material to be inserted and released; a negative electrode plate group formed by winding the negative electrode plate through a separator; A battery can body electrically connected to one of the current collector and the negative electrode current collector; and a battery can body electrically connected to the other current collector of the positive electrode current collector and the negative electrode current collector; In a lithium ion battery comprising: a terminal member attached to the battery can body via an insulating material; wherein the one of the positive electrode current collector and the negative electrode current collector has an active material layer formed on a surface. However, the second projecting from one end of the spiral electrode group The positive electrode current collector and the other current collector of the negative electrode current collector do not have an active material layer formed on the surface thereof, and the other of the spiral electrode group A second exposed portion integrally protruding from an end of the first and second exposed portions, wherein the first exposed portion and the second exposed portion are directly connected to the terminal member and the battery can body, respectively. A lithium-ion battery characterized by the following.